Method of forming a sharp-edged lockwasher



March 8, 1966 HOPP EIAL METHOD OF FORMING A SHARP-EDGED LOCKWASHER 2Sheets-Sheet 1 Filed May 24, 1963 ii ii PRIOR AIET PRIOR ART March 8,1966 H. P. HOPP ET AL 3,238,543

METHOD OF FORMING A SHARP-EDGED LOCKWASHER Filed May 24, 1965 2Sheets-Sheet 2' 7 W I 60 MN I United States Patent 3,238,543 METHOD OFFGRMING A SHARP-EDGED LOCKWASHER Harold P. Hopp, 372 Lantana Ave.,Englewood, N..I.,

and Rudolf Bohm, New York, N.Y.; said Bohm assignor to said Hopp FiledMay 24, 1963, Ser. No. 283,004 2 Claims. (CI. -86) This inventionrelates generally to the field of metal stamping, and more particularlyto an improved lock washer or similar article and method of making thesame.

Planar annular lock washers are well-known in the art, and have for manyyears been widely used for maintaining threaded interconnections intightened condition. Lock washers of this general type are provided witha central opening through which the threaded bolt may project, and theinner or outer periphery of the washer is provided with teeth formingsharpened edges which cut into the surface of either the underportion ofthe screw or bolt head, or the corresponding abutting surface of anothermember. In the past, such lock washers have normally been formed bystamping operations, and burred edges, which are quite sharp, have beenformed as an incidental result of the stamping operation, and haveobtained a locking purchase in most cases sufi'icient to adequatelysecure the threaded member in position and vibrat-ion from loosening thesame. Ideally, a lock wash- "er should provide sharpened edgesprojecting from both planar surfaces in order that this purchase isobtained on both of the interlocking members and not merely one of them.Owing to considerations of cost of fabrication, where lock washers ofthis type are formed by simple die stamping operations, this desired endhas not been readily achieved.

In our prior patent No. 3,060,992, granted October 30, 1962, andentitled Means and Method for Forming Non- Planar Articles, we havedisclosed a lock washer cut from sheet stock material in which sharpenedprojections extend axially out of the plane of the washer in bothdirections. These projections make point contact, and ofier to aconsiderable extent the desired result which is a scoring or diggingaction on both the undersurface of the screw head and the plate againstwhich the screw head abuts. We have found, however, that it is possibleto obtain a superior efiect by the method herein disclosed.

It is among the principal objects of the present invention to provide animproved lock washer or similar article in which sharp edges extend overa considerable area and away from the plane of the lock washer in eitherof two directions.

Another object of the invention lies in the provision of an improvedmeans for forming a lock washer or similar article in which sharp edgesextending from two oppositely disposed surfaces are formed as a resultof a multiple stage stamping operation.

Another object of the invention lies in the provision of an improvedlock washer of the class described capable of imparting increasedpurchase against each of two abutting surfaces between which it isdisposed.

A further object of the invention lies in the provision of an improvedmethod for form-ing an improved lack washer, in which sharp edges areformed as a result of partially punching the same from the sheet stockof which it is formed, and completely punching the same back through theopening formed as a result of the first punching operation to result inthe formation of sharp edges extending in either of two oppositelydisposed directions.

Another object of the invention lies in the provision of an improvedlock washer in which the cost of fabrication may be directly comparablewith that of existing ICC lock washer construction, thereby permittingconsequent wide sale, distribution and use.

Still another object of the invention lies in the provision of animproved method for forming lock washers of improved type which may bereadily incorporated into existing punch press constructions with littleor no adjustment thereof.

A feature of the invention lies in the ready adaptability of the methodto a wide variety of shapes and sizes of lock washers, as the employmentof the method does not depend upon the particular outer configuration ofthe formed article.

These objects and features, as well as other incidental ends andadvantages, will more fully appear in the progress of the followingdisclosure, and be pointed out in the appended claim-s.

In the drawings, to which references will he made in the specification,similar reference characters have been employed to designatecorresponding parts throughout the several views.

FIGURE 1 is a view in perspective of a lock washer or similar articleformed in accordance with the present invention.

FIGURE 2 is a fragmentary view in elevation of one of the .teeth of thelock washer seen in FIGURE 1, showing the teeth of the lock washer seenin FIGURE 1, showing the same positioned between two abutting surfaces,and just prior to the exertion of a compression thereupon.

FIGURE 3 is a schematic view, partially in section, showing the punchingof an article from sheet stock in accordance with prior art methods.

FIGURE 4 is a schematic sectional view showing the product obtained as aresult of the operation shown in FIGURE 3.

FIGURE 5 is a schematic sectional view showing an operation similar tothat illustrated in FIGURE '3, in which the male die is provided with anangularly disposed face.

:FIGURE 6 is a sectional view corresponding to that seen in FIGURE 4,but showing the product obtained as a result of the operation shown inFIGURE 5.

FIGURE 7 is an exploded view in elevation, partly in section, showing animproved male and female die means in accordance with the presentinvention.

FIGURE 8 is a fragmentary plan view of partially blanked sheet metalstock, being the product of the die means illustrated in FIGURE 7.

FIGURE 9 is a fragmentary side elevational view as might be seen fromthe lower portion of FIGURE 8.

FIGURE 10 is a schematic view, partly in section, showing a second maleand 'female die means employed in accordance with the present invention.

FIGURE 11 is a sectional view corresponding to the product obtained fromoperation of the die means shown in FIGURE 10.

FIGURE 12 is a schematic side elevational view, partly in section,showing serial operation of the die means illustrated in FIGURES 7 and10.

In accordance with the invention, there is illustrated in FIGURE 1 inthe drawings a completed lock washer or similar article, generallyindicated by reference char-.

acter 19, and resembling in most respects the lock washer disclosed inour above-mentioned prior patent 3,060,- 9212. The washer includes acentral opening 11, first and second planar surfaces 12 and 13,respectively, and a plurality of teeth 14, first portions '15 of whichextend upwardly from the first planar surface 12, and second portions 16of which extend downwardly from the second planar surface 13. Bycutting, in accordance with the teaching of. the above-mentioned patent,there are formed first and second sharp points 17 and 1 8 which areadapted to cut into each of first and second abutting surfaces 19 and 20on objects such as a nut and bolt, sheet, or other structure. Whenmanufactured in accordance with our prior patent, the stamping of thefinished product is done by a single set of dies resembling to a degreethe schematic illustration in FIGURE 3. In this view, there isillustrated a male die member 22, and a female die member 23, betweenwhich there is disposed a sheet 24 of metallic stock. The shearing edges25 of the male die member 22, and 26 of the female die mem ber 23, passeach other during the stamping operation to blank out the finishedobject, which is illustrated in FIG- URE 4. The blank 27, as completed,includes a first surface 28 formed by the face of the male die member22, the surface being bounded by a sharp peripheral edge 29. The secondsurface 30 defined by the female die member 23 is bounded by arelatively rounded peripheral edge 31. It is to be noted that theillustration of the edges 29 and 31 in FIGURE 4 is greatly exaggeratedfor purposes of clarity, since in most cases the sharpness of the edge29 will be observable only on critical examination with the naked eye,and is caused by the plastic flow of metal occurring while the dieelements are pressing upon the metal, and prior to severance of theformed part.

Referring to FIGURE 5, there is schematically illustrated a similar diestamping operation in which the male die 33 is provided with anangularly disposed face 34, so that the stamping action is of aprogressive shearing nature, and the angular face 34 may partially formas Well as cut the finished article, as taught in our above-mentionedpatent, No. 3,060,992. The shearing edge 35, as illustrated in FIGURE 5,will have passed through the plane of the stock 38 at the leftwardmostportion thereof, before the rightwardmost portion has entered the planeof the stock. The female die 36 includes a shearing edge 37 lying in aplane substantially perpendicular to the axis of movement of the maledie member 36. Under such conditions, the severed blank 39 will assumethe appearance shown in 'FIGURE 6, wherein the first surface 40 andsecond surface 41 are angularly disposed with respect to the edgesurface. The first surface 40 will terminate in a sharpened edge 42extending upwardly therefrom. I

Referring to FIGURE 7, there is illustrated a die element 45 employed inpracticing the present invention, the same including a plurality ofindividual tooth-cutting members 46, as well as first and secondgenerally oppositely disposed cutting members 47 and 48 in which thepointed portions thereof have been ground off. The corresponding femaledie element 49 is conventional, and mates with the male die element 45.During the stamping operation, using the die elements 45 and 49, themale die element 45 enters the female die element 49 to a pointindicated by the dashed line in FIGURE 7, so that the cutting members 47and 48 will only partially shear the blank, and allow the same to remainattached to and parallel to the plane of the stock. In this operation,the male die element 45 is placed below the stock as shown in FIGURE 7.

As seen in FIGURES 8 and 9, the stock 53, after a series of suchoperations, includes a plurality of formed but unsevered washers 54,each connected at first and second points of interconnection and 56. Thestock in this condition is fed to a second set of male and female dieelements 58 and 59, respectively, for a second stamping operation asillustrated in FIGURE 10. The die elements 58 and 59 are reversed inorientation with respect to the die elements 45 and 49, and aresubstantially identical except that the members 47 and 48 :areeliminated, as the second set of die elements performs a completestamping operation which severs the completed article from the stock.FIGURE 11 illustrates a schematic sectional view in which first andsecond relatively sharp edges 62 and '63, respectively, are oppositelydisposed, the first sharp edge 62 having been formed by the finalpunching operation, and the second edge 63 having been formed by theinitial punching operation, whereby the completely severed Washer 54 isprovided with sharpened edges which project from both planar surfaces 64and 65 thereof.

The edge 62 is formed by the final punching operation by virtue ofinterference existing between the previously formed washer '54 and theedge of the opening 54a (see FIGURE 10) in the stock from which thewasher is cut. During the initial punching operation, the clearancebetween the female die 67 and the male die '68 causes metal to flow atthe points of shear. It is this metal flow which causes the formation ofthe edge 63. When the washer is again forced back through the opening54a, the decrease in size of the opening caused by the above-mentionedflow of metal causes a rubbing or interference between the peripheralsurfaceof the opening 54a and the washer 54, a flow of metal in bothpieces tending to move the metal in a direction opposite that of theinitial flow.

We wish it to be understood that we do not consider the inventionlimited to the precise details of structure shown and set forth in thisspecification, for obvious modifications will occur to those skilled inthe art to which the invention pertains.

We claim:

1. The method of forming a generally planar toothlock washer or similararticle having sharp edges thereon extending longitudinally outward inopposite directions from the plane of said lockwasher, comprising thesteps of:

(a) providing a first set of mating male and female die elements havingprincipal coaxial axes, said die elements having a first direction ofrelative movement;

(b) providing a second set of corresponding male and female die elementshaving principal coaxial axes, and a second direction of relativemovement opposite said first direction of relative movement;

(c) providing sheet stock material and positioning the same between saidfirst set of die elements and substantially completely forming and atleast partially severing said lockwasher from said stock, said formingand severing operation also forming a corresponding opening in saidstock and a simultaneous first flow of metal resulting in the formationof a first sharpened edge on said lockwasher at a surface contacting themale die element of said first set of die elements;

(d) positioning said stock between said second set of die elements andforcing said completed washer back through said opening in said stockwhereby interference resulting from said first flow of metal causes asecond flow of metal in said washer and the formation of a sharp edge ona surface contacting the male die element of said second set of dieelements.

2. The method of forming a generally planar toothlock washer or similararticle having sharp edges thereon extending longitudinally outward inopposite directions from the plane of said lockwasher, comprising thesteps of:

(a) providing a first set of mating male and female die elements havingprincipal coaxial axes, said die elements having a first direction ofrelative movement;

(b) providing a second set of corresponding male and female die elementshaving principal coaxial axes, and a second direction of relativemovement opposite said first direction of relative movement;

(0) providing sheet stock material and positioning the same between saidfirst set of die elements and substantially completely forming and atleast partially severing said lockwasher from said stock, said formingand severing operation also forming a corresponding opening in saidstock and a simultaneous first flow of metal resulting in the formationof a first sharpened edge on said lockwasher at a surface contacting themale die element of said first set of die elements;

(d) positioning said stock between said second set of die elements andforcing said completed washer back through said opening in said stockwhereby interfer- 5 ence resulting from said first flow of metal causesa second flow of metal in said washer and the formation of a sharp edgeon a surface contacting the male die element of said second set of dieelements and shearing said lockwasher completely from said stock.

References Cited by the Examiner UNITED STATES PATENTS 1,785,281 12/1930Olson 10 73 2,508,758 5/1950 Hollerith 83-51 3,060,992 10/1962 Hopp eta1 153 2 ANDREW R. JUHASZ, Primary Examiner.

1. THE METHOD OF FORMING A GENERALLY PLANAR TOOTHLOCK WASHER OR SIMILARARTICLE HAVING SHARP EDGES THEREON EXTENDING LONGITUDINALLY OUTWARD INOPPOSITE DIRECTIONS FROM THE PLANE OF SAID LOCKWASHER, COMPRISING THESTEPS OF: (A) PROVIDING A FIRST SET OF MATING MALE AND FEMALE DIEELEMENTS HAVING PRINCIPAL COAXIAL AXES, SAID DIE ELEMENTS HAVING A FIRSTDIRECTION OF RELATIVE MOVEMENT; (B) PROVIDING A SECOND SET OFCORRESPONDING MALE AND FEMALE DIE ELEMENTS HAVING PRINCIPAL COAXIALAXES, AND A SECOND DIRECTION OF RELATIVE MOVEMENT OPPOSITE SAID FIRSTDIRECTION OF RELATIVE MOVEMENT; (C) PROVIDING SHEET STOCK MATERIAL ANDPOSITIONING THE SAME BETWEEN SAID FIRST SET OF DIE ELEMENTS ANDSUBSTANTIALLY COMPLETELY FORMING AND AT LEAST PARTIALLY SEVERING SAIDLOCKWASHER FROM SAID STOCK, SAID FORMING SAID SEVERING OPERATION ALSOFORMING A CORRESPONDING OPENING IN SAID STOCK AND A SIMULTANEOUS FIRSTFLOW OF METAL RESULTING IN THE FORMATION OF A FIRST SHARPENED EDGE ONSAID LOCKWASHER AT A SURFACE CONTACTING THE MALE DIE ELEMENT OF SAIDFIRST SET OF DIE ELEMENTS; (D) POSITIONING SAID STOCK BETWEEN SAIDSECOND SET OF DIE ELEMENTS AND FORCING SAID COMPLETED WASHER BACKTHROUGH SAID OPENING IN SAID STOCK WHEREBY INTERFERENCE RESULTING FROMSAID FIRST FLOW OF METAL CAUSES A SECOND FLOW OF METAL IN SAID WASHERAND THE FORMATION OF A SHARP EDGE ON A SURFACE CONTACTING THE MALE DIEELEMENT OF SAID SECOND SET OF DIE ELEMENTS.